In the art of electrophotography, there is a need for low-cost, hydrolytically stable, low surface adhesion (LSA) additives for electrographic toner powders. LSA additives provide improved transfer of toner from the photoconductor to the receiver and increase the developer life. LSA additives should be cost effective and stable in order to maintain good manufacturing control of the toner composition.
To achieve such results, various approaches have been tried. One approach has been to utilize block copolymer LSA additives produced by copolymerizing a primary amine-terminated silicone oil, which reduces surface adhesion, with a polyester. The synthesis of these LSA additives is expensive and requires the use of acid and base washes that result in degradative hydrolysis of the LSA additive. Hydrolysis results in a lowering of the molecular weight of the polyester block over time which can undesirably produce variability of the dispersion quality of the LSA additive in the toner powder.
Another approach has been to admix, without reacting, a silicone oil with a toner powder. However, these admixtures are unsatisfactory because the silicone oil is not immobilized which can cause premature failure of the developer.
So far as is now known, prior art approaches have not solved the problem of producing a low cost, hydrolytically stable LSA additive.